Study On The Extraction Method Of Flavonoids By Deep Eutectic Solvent

The rapid development of modern science and technology provides a new way for the extraction and functional research of active ingredients of natural products,and the related research and practice are also deepening.At present,low-toxicity,environment-friendly,inexpensive and easy-to-operate solvent extraction methods are one of the hotspots in the field of natural product chemistry.Researchers are paying more and more attention to extraction solvents such as ionic liquids,supercritical fluids,and deep eutectic solvents.Two-component or three-component deep eutectic solvents prepared from hydrogen bond acceptors and hydrogen bond donors,the melting point of which is significantly lower than the melting point of the pure substances of each component,used in natural product chemistry,electrochemistry,organic synthesis and medicine It has great application potential in fields such as release.In this paper,11 deep eutectic solvents with different molar ratios were selected,their preparation technology was studied,and the density,viscosity and density were analyzed.Deep eutectic solvent was used to extract flavonoids from bayberry leaves and melon peel,and macroporous resin was used to separate and purify the extracts,and the contents of myricetin and rutin were determined to optimize the extraction process;Finally,the antioxidant activity of rutin and myricetin was studied.The main research work is as follows:（1）Deep eutectic solvent preparation and physical properties were studied.It was found that under the same conditions as hydrogen bond acceptor and hydrogen bond donor,the preparation of deep eutectic solvent consumes less time as the molar ratio of hydrogen bond donor increases.The viscosity of the deep eutectic solvent decreases as the temperature rises,and the viscosity of the deep eutectic solvent is related to the viscosity of the hydrogen bond donor.The density of the deep eutectic solvent is determined by the hydrogen bonding donor,which is a polyol with a lower density value.（2）The extraction,separation and antioxidant activity of flavonoids from bayberry leaves were studied.The study found that using 11 kinds of deep eutectic solvents with a moisture content of 30% to extract myricetin in myricetus leaves,compared with the use of ethanol with a volume fraction of 80%,the combination of DES-5（choline chloride-oxalic acid）could obtain better results.good extraction results.The results of response surface methodology showed that the optimal extraction conditions were as follows: water content19 %,liquid-solid ratio 37:1 m L/g,extraction temperature 72 ℃,extraction time 45 min,under these conditions,the extraction amount of myricetin was 21.58 mg/g.The optimal combination of extracts was adsorbed and desorbed by AB-8 macroporous adsorption resin,and the best results obtained were that the adsorption rate was 1 BV/hr,the desorption rate using absolute ethanol was 1 BV/hr,and the desorption volume was 2 BV.In the research on the antioxidant activity of myricetin by DPPH method and ·OH radical method,the scavenging rate of myricetin at the concentration of 2 μg/m L～16 μg/m L is better than that of Vc.（3）The extraction,separation and antioxidant activity of flavonoids in Gualou peel were studied.The study found that the rutin in Gualou peel was extracted by using 80% methanol and prepared 11 deep eutectic solvent with a water content of 30%,and DES-3（choline chloride-ethylene glycol）was used to obtain rutin.better extraction effect.The optimal extraction process conditions optimized by response surface methodology were as follows:water content 36 %,liquid-solid ratio 25 : 1 m L/g,extraction temperature 57 ℃,extraction time 34 min,under these conditions,the extraction amount of rutin was 28.77 μg/g.The rutin in Psidium guajava bark was separated and purified using AB-8 macroporous resin,desorbed in methanol and spun off.The concentration of rutin in the peel of Fructus Guarana has a good antioxidant effect on DPPH in the range of 20 μg/m L～180 μg/m L;The scavenging rate of ·OH radicals gradually increased in the range of 20 μg/m L to 160 μg/m L between Vc and rutin in Psidium guajava,and the antioxidant effect of rutin in Psidium guajava was slightly worse than that of Vc.